1. Field of the Invention
The present invention relates to a thermoelectric device having thermoelectric properties.
2. Description of the Related Art
Thermoelectric devices utilizing thermoelectric properties of materials are investigated. Examples of a thermoelectric device using the Seebeck effect include a power-generating device utilizing a temperature difference between the outside air and human bodies, and a power-generating device utilizing waste heat from automotive cars, incinerators, heating devices, or the like. Examples of a thermoelectric devices using the Peltier effect include cooling devices for CPU and a laser medium. In particular, the power generating device utilizing a temperature difference attracts attention as an energy harvesting component.
Thermoelectric devices which have been investigated are bulk-type devices using bulk materials such as bismuth-tellurium (BiTe)-based, lead-tellurium (PbTe)-based, silicide-based, or oxide-based materials, or the like. However, the bulk-type devices have very low power factor.
Japanese Unexamined Patent Application Publication No. 2000-244023 proposes, as a thermoelectric device using a thin film, a hetero-structure thermoelectric device including a carrier supply layer t which an additive is added and which has a predetermined band gap, and a high-purity layer which has a band gap smaller than that of the carrier supply layer. Also, silicon/silicon germanium (hereinafter referred to as “Si/SiGe”) is described as an example of the carrier supply layer/high-purity layer.